This invention relates generally to wellbore casings, and in particular to wellbore casings that are formed using expandable tubular members.
Conventionally, when a wellbore is created, a number of casings are installed in the borehole to prevent collapse of the borehole wall and to prevent undesired outflow of drilling fluid into the formation or inflow of fluid from the formation into the borehole. The borehole is drilled in intervals whereby a casing which is to be installed in a lower borehole interval is lowered through a previously installed casing of an upper borehole interval. As a consequence of this procedure the casing of the lower interval is of smaller diameter than the casing of the upper interval. Thus, the casings are in a nested arrangement with casing diameters decreasing in downward direction. Cement annuli are provided between the outer surfaces of the casings and the borehole wall to seal the casings from the borehole wall. As a consequence of this nested arrangement a relatively large borehole diameter is required at the upper part of the wellbore. Such a large borehole diameter involves increased costs due to heavy casing handling equipment, large drill bits and increased volumes of drilling fluid and drill cuttings. Moreover, increased drilling rig time is involved due to required cement pumping, cement hardening, required equipment changes due to large variations in hole diameters drilled in the course of the well, and the large volume of cuttings drilled and removed. expandable tubular member by pulling the expansion cone through the expandable tubular member. The expandable tubular member includes: a first tubular member, a second tubular member, and a threaded connection for coupling the first tubular member to the second tubular member. The threaded connection includes: one or more sealing members for sealing the interface between the first and second tubular members.
According to another aspect of the present invention, a method of coupling an expandable tubular member to a preexisting structure is provided that includes positioning the expandable tubular member and an expansion cone within the preexisting structure, anchoring the expandable tubular member to the preexisting structure, and axially displacing the expansion cone relative to the expandable tubular member by pulling the expansion cone through the expandable tubular member. The expandable tubular member includes a plurality of tubular members having threaded portions that are coupled to one another by the process of: coating the threaded portions of the tubular members with a sealant, coupling the threaded portions of the tubular members and curing the sealant.
According to another aspect of the present invention, a method of coupling a tubular member to a preexisting structure is provided that includes positioning the tubular member and an expansion cone within the preexisting structure, anchoring the tubular member to the preexisting structure, and axially displacing the expansion cone relative to the tubular member by pulling the expansion cone through the expandable tubular member. The tubular member includes: a pair of rings for engaging the preexisting structure, and a sealing element positioned between the rings for sealing the interface between the tubular member and the preexisting structure.
According to another aspect of the present invention, a method of coupling a tubular member to a preexisting structure is provided that includes positioning the expandable tubular member and an expansion cone within the preexisting structure, anchoring the expandable tubular member to the preexisting structure, and axially displacing the expansion cone relative to the expandable tubular member by pulling the expansion cone through the expandable tubular member. The tubular member includes one or more slots.
The present invention is directed to overcoming one or more of the limitations of the existing procedures for forming wellbores.